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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-06-29 12:08:26 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-08-11 13:09:14 -0700
commit23a9b748a3d27f67cdb078fcb891a920285e75d9 (patch)
tree3939c14a9385cb193210f2fb20e0edf4b96cf55b /kernel/sched
parentf274f1e72d7171c80c8c790040e47a23a74796b6 (diff)
sched: Replace spin_unlock_wait() with lock/unlock pair
There is no agreed-upon definition of spin_unlock_wait()'s semantics, and it appears that all callers could do just as well with a lock/unlock pair. This commit therefore replaces the spin_unlock_wait() call in do_task_dead() with spin_lock() followed immediately by spin_unlock(). This should be safe from a performance perspective because the lock is this tasks ->pi_lock, and this is called only after the task exits. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> [ paulmck: Drop smp_mb() based on Peter Zijlstra's analysis: http://lkml.kernel.org/r/20170811144150.26gowhxte7ri5fpk@hirez.programming.kicks-ass.net ]
Diffstat (limited to 'kernel/sched')
-rw-r--r--kernel/sched/core.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 17c667b427b4..5d22323ae099 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -3352,8 +3352,8 @@ void __noreturn do_task_dead(void)
* To avoid it, we have to wait for releasing tsk->pi_lock which
* is held by try_to_wake_up()
*/
- smp_mb();
- raw_spin_unlock_wait(&current->pi_lock);
+ raw_spin_lock_irq(&current->pi_lock);
+ raw_spin_unlock_irq(&current->pi_lock);
/* Causes final put_task_struct in finish_task_switch(): */
__set_current_state(TASK_DEAD);